All good points. But what he/she does have is MFK, and from what i can tell at least a willingness to do research and learn before jumping off "into the deep end".
If zugs were to start a thread "how to set up my new 300 yada yada" and be able to absorb at least half of the advice the helpful people on this site would surely give, then I'd say he's off to a great start. My own start into fishkeeping involved several failures over years (including at least one "boiling pot of death") but it wasnt until i started researching and posting here that i began having success keeping fish healthily and happily.
I wont lie and say keeping a 300 is just as easy as a 75. It is more maintenance and time for sure. But give the guy/girl a chance, they may very well be up to the challenge.